Playing the Sound of Healthy Coral Reefs Aids Coral Reefs’ Recovery

Coral reefs are vital to marine wildlife, as they provide shelter for nearly one quarter of all known marine species. Climate change and local anthropogenic stressors pose the biggest threat to coral reefs globally, and are causing unprecedented levels of damage. New research has found an innovative way to restore degraded coral reef habitat, by playing the sound of healthy coral reefs through underwater speakers.

A team of international researchers led by the marine biologist and PhD student Tim Gordon, based at the University of Exeter, has recently experimented a novel way to attract greater fish diversity to degraded coral reefs, which can be beneficial for their restoration. In their study1 published this week in Nature Communications, the authors used loudspeakers to broadcast the sound of healthy coral reefs on experimental coral-rubble patch reefs for 40 days, on Australia’s northern Great Barrier Reef.

In the wild, young fish spend their larval stage in the open ocean and use a range of sensory cues to locate and settle into coral reef habitat, including acoustic cues. However, the authors explain, “degraded reefs smell and sound less attractive to juvenile fishes, and receive lower levels of fish settlement than healthy systems”. Since fish play a key role in the recovery of coral reefs through performing a series of services, fewer fish visits mean less chances for reef recovery.

Through their experiment, the authors found that the reefs with the speakers attracted and maintained higher fish abundance than reefs without speakers. Acoustically enriched reefs also attracted fish populations at a faster rate.

“[S]urveys after 40 days revealed that there were significantly more herbivores, omnivores, planktivores, invertivores and piscivores on acoustically enriched reefs than on acoustically unmanipulated reefs, with no significant differences between the two control groups”, the authors say in their paper.

Effects of acoustic enrichment on different trophic groups. Mixed-effects models revealed significant effects of loudspeaker treatment in all five trophic guilds; different letters associated with boxplots represent significant differences in post-hoc Tukey’s HSD tests; Figure and description credits:1

These results suggest that acoustically enhancing coral reefs may represent a useful conservation tool. “Further work is now needed to investigate the translatability of this finding into different reef habitats and geographical contexts”, the authors conclude.

Higher water temperatures in 2016 caused the worst destruction of corals ever recorded on Australia’s Great Barrier Reef, with up to 67% of corals dying in the reef’s northern section2.

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References

  1. Gordon, T.A., Radford, A.N., Davidson, I.K., Barnes, K., McCloskey, K., Nedelec, S.L., Meekan, M.G., McCormick, M.I. and Simpson, S.D., 2019. Acoustic enrichment can enhance fish community development on degraded coral reef habitat. Nature Communications10(1), pp.1-7.
  2. ARC Centre of Excellence for Coral Reef Studies. 2016. Annual Report 2016. Available at https://www.coralcoe.org.au/wp-content/uploads/2017/04/CRS-Annual-Report-2016-Web.pdf

Featured image cover: https://bit.ly/2sAdGJZ

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